Ecology

Parasite found in renal sacs of Cephalopods. Chromidina chattoni type host is Loligo vulgaris. Chromidina chattoni has not yet been described in other hosts.

Life cycle

Life Cycle: Chromidina spp. have a polymorphic dixenous life cycle, with two different budding processes which are monotomy and palintomy. The adult stage, the vermiform tropho-tomont, has a maximum body length varying from 400 µm to 2,000 µm. Some rare adult stages can have an accelerated growth process. Their size increases so quickly that their length can measure up to 5,000 µm. Given their unusual extended size, these adult stages are called hypertrophonts. The tropho-tomont is uniformly ciliated and has no cytostome. It is attached through its anterior end to the host kidney tissues with its body bathing in the renal fluids, and feeds by nutriment absorption from host cells and fluids. Division by monotomy produces a single long bud from the posterior end, the apotomite, which is morphologically similar to its parent and develops into a second generation of trophotomonts after detachment and colonisation of the host kidney. Division by palintomy produces smaller buds that form a typical chain of individuals attached to the tropho-tomont, which differentiate into tomites. Budding occurs only from the posterior end. The tomite is a small ciliate form with a unique ciliature and a cytostome. When detached, it is believed that the tomite leaves the renal appendages to be released with passage of urine into the sea. This stage is presumed to encyst, as a phoront, and to infest an intermediate host. However, no intermediate host has been confirmed so far. In Souidenne et al., 2016.

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This web site was designed by Laure Guillou and Fabrice Not (Biological station of Roscoff, CNRS, France). Contributions or suggestions are very welcome and can be submitted either to Laure Guillou or to Fabrice Not.